A blackboard system is an artificial intelligence application based on the blackboard architectural model, where a common knowledge base, the "blackboard", is iteratively updated by a diverse group of specialist knowledge sources, starting with a problem specification and ending with a solution. Each knowledge source updates the blackboard with a partial solution when its internal constraints match the blackboard state. In this way, the specialists work together to solve the problem. The blackboard model was originally designed as a way to handle complex, ill-defined problems, where the solution is the sum of its parts.
The following scenario provides a simple metaphor that gives some insight into how a blackboard functions:
A group of specialists are seated in a room with a large blackboard. They work as a team to brainstorm a solution to a problem, using the blackboard as the workplace for cooperatively developing the solution. The session begins when the problem specifications are written onto the blackboard. The specialists all watch the blackboard, looking for an opportunity to apply their expertise to the developing solution. When someone writes something on the blackboard that allows another specialist to apply their expertise, the second specialist records their contribution on the blackboard, hopefully enabling other specialists to then apply their expertise. This process of adding contributions to the blackboard continues until the problem has been solved.
A blackboard-system application consists of three major components
- The software specialist modules, which are called knowledge sources (KSs). Like the human experts at a blackboard, each knowledge source provides specific expertise needed by the application.
- The blackboard, a shared repository of problems, partial solutions, suggestions, and contributed information. The blackboard can be thought of as a dynamic "library" of contributions to the current problem that have been recently "published" by other knowledge sources.
- The control shell, which controls the flow of problem-solving activity in the system. Just as the eager human specialists need a moderator to prevent them from trampling each other in a mad dash to grab the chalk, KSs need a mechanism to organize their use in the most effective and coherent fashion. In a blackboard system, this is provided by the control shell.
More recent examples include deployed real-world applications, such as the PLAN component of the Mission Control System for RADARSAT-1, an Earth observation satellite developed by Canada to monitor environmental changes and Earth's natural resources.
GTXImage CAD software by GTX Corporation was developed in the early 1990s using a set of rulebases and neural networks as specialists operating on a blackboard system.
Adobe Acrobat Capture (now discontinued) used a Blackboard system to decompose and recognize image pages to understand the objects, text, and fonts on the page. This function is currently built into the retail version of Adobe Acrobat as "OCR Text Recognition".
See also 
- Erman, L. D.; Hayes-Roth, F.; Lesser, V. R.; Reddy, D. R. (1980). "The Hearsay-II Speech-Understanding System: Integrating Knowledge to Resolve Uncertainty". ACM Computing Surveys 12 (2): 213. doi:10.1145/356810.356816.
- Hayes-Roth, B. (1985). "A blackboard architecture for control". Artificial Intelligence 26 (3): 251–321. doi:10.1016/0004-3702(85)90063-3.
- Nii, H. Yenny (1986). Blackboard Systems (Technical report STAN-CS-86-1123). Department of Computer Science, Stanford University. ftp://reports.stanford.edu/pub/cstr/reports/cs/tr/86/1123/CS-TR-86-1123.pdf. Retrieved 2013-04-12.
- Craig, Iain (1995). Blackboard Systems. Norwood, NJ: Ablex. ISBN 0-89391-594-7.
- Corkill, Daniel D.; Gallagher, Kevin Q.; Johnson, Philip M. (July 1987). "Achieving flexibility, efficiency, and generality in blackboard architectures". Proceedings of the National Conference on Artificial Intelligence. Seattle, Washington. pp. 18–23. http://dancorkill.home.comcast.net/pubs/aaai87.pdf.
- Englemore, Robert; Morgan, Tony (1988). Blackboard Systems. Addison-Wesley. ISBN 0-201-17431-6.
- Jagannathan, Vasudevan; Dodhiawala, Rajendra; Baum, Lawrence S., eds. (1989). Blackboard Architectures and Applications. Academic Press. ISBN 0-12-379940-6.
- Carver, Norman (May 1997). "A Revisionist View of Blackboard Systems". Proceedings of the 1997 Midwest Artificial Intelligence and Cognitive Science Society Conference. http://www.cs.siu.edu/~carver/ps-files/maics97.ps.gz.
- Corkill, Daniel D. (September 1991). "Blackboard Systems". AI Expert 6 (9): 40–47.
- Corkill, Daniel D. (1989). "Design Alternatives for Parallel and Distributed Blackboard Systems". In Jagannathan, V.; Dodhiawala, Rajendra; Baum, Lawrence S. Blackboard Architectures and Applications. Academic Press. pp. 99–136.
- Corkill, Daniel D. (May 1997). "Countdown to Success: Dynamic objects, GBB, and RADARSAT-1". Communications of the ACM 40 (5): 48–58.
- Corkill, Daniel D. (October 2003). "Collaborating Software: Blackboard and Multi-Agent Systems & the Future.". In Proceedings of the International Lisp Conference. New York, New York. http://dancorkill.home.comcast.net/~dancorkill/pubs/ilc03.pdf.
- Corkill, Daniel D. (March 2011). "GBBopen Tutorial". The GBBopen Project. Retrieve PDF Article
- Open Blackboard System An open source framework for developing blackboard systems.
- BBTech Corporation A company that develops and maintains blackboard applications.
- GBBopen An open source blackboard system framework.
- SQLBusRT A blackboard implementation with temporal historical data added.
- KOGMO-RTDB A real-time open source blackboard for C/C++, used by some DARPA Urban Challenge autonomous vehicles.
- HarTech Technologies A company that provides both Simulation and Command and Control solutions which are all based on a unique Blackboard architecture. The Blackboard development framework can be utilized to develop own costume applications.
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